Polysiloxane-polyalkyleneglycol block copolymers suitable as foam stabilizers in the manufacture of polyurethane foams

ABSTRACT

Novel polysiloxane-polyalkyleneglycol block copolymers suitable as foam stabilizers in the preparation of flexible polyurethane foams. The novel block copolymers are characterized by the formula A B y, wherein

United Rossmy et a1.

[451 Mar. 27, 1973 Koerner, Mulheim (Ruhr), both of Germany [73]Assignee: The Goldschmidt A.G., Essen, Germany [22] Filed: Jan. 25, 1971[21] Appl. No.: 109,699

Related U.S. Application Data [63] Continuation-impart of Ser. No.687,459, Dec. 4,

1967, abandoned.

[52] US. Cl..260/448.2 B, 260/2.5 AM, 260/465 Y,

260/4488 R [51 lint. Cl. ..C07f 7/08, C07f 7/18 [58] Field of Search..260/448.2 B, 448.8 R

[56] References Cited UNITED STATES PATENTS 2/1965 Black et al...260/448.2 B 5/1965 Holdstock....

3,271,331 9/1966 Ender 260/448 2 B X 3,272,762 9/1966 Ibbotson et al......260/448.2 B X 3,280,160 10/ 1966 Bailey ..260/448.8 R 3,299,1 l3l/l967 Haluska... ..260/448.8 R 3,341,338 9/1967 Pater 260/4482 B X3,342,766 9/1967 Huntington ....260/448.2 B X 3,402,192 9/1968' Haluska..260/448.2 B 3,420,782 l/1969 Dahm et a! ....260/448.2 B X 3,457,1737/1969 Pater ..260/448.2 B X Primary Examiner-Daniel E. Wyman AssistantExaminer-Paul F. Shaver Attorney-McGlew & Toren 7 1 ABSTRACT Novelpolysiloxane-polyalkyleneglycol "blocli copolymers suitable as foamstabilizers in the preparation of flexible polyurethane foams. The novelblock copolymers are characterized by the formula A B y, wherein yis=1.75 to 5;

A indicates the polysiloxane moiety of the block copolymer and beingcharacterized by a mole weight of between about 250 y to 1000 y, 1.9 to2.02 alkyl and alkoxy groups on the average being associated with eachsilicon atom, the alkyl and alkoxy groups containing one to four carbonatoms, at least 90 mole percent of the alkyl groups being methyl and thealkoxy groups being present in an amount of at least 10 mole percentcalculated on the alkyl groups;

B indicates the polyalkyleneglycol monoalkylether moiety or polyalkyleneglycol monoarylether moiety which is characterized by a mole weight ofbetween about 2400 to 5000, wherein the alkyl group has one to sixcarbon atoms and the polyalkyleneglycol residue is composed on the onehand of alkyleneoxy groups of the formula and/or (CH O- and, on theother hand, of the group -(CH O in a weight ratio of about 50:50 to70:30; and

wherein A and B are linked to each other by divalent groups beingoxygen, alkylene of one to four carbon atoms, --(CH COO- or (CH COO-.

The application also discloses a process of preparing polyurethanefoams, wherein the novel block copolymers are used as foam stabilizer.

15 Claims, No Drawings POLYSILOXANE-POLYALKYLENEGLYCOL BLOCK COPOLYMERSSUITABLE AS FOAM STAEILIZERS IN THE MANUFACTURE OF POLYURETHANE FOAMSThis application is a continuation-in-part of Ser. No.

687,459, filed 12/4/67, now abandoned.

SUMMARY OF THE INVENTION rethane foams by a one stage reaction ofpolyalkyleneglycol with polyisocyanates. The reaction system for thisreaction comprises water and/or an organic propellant as, for example, ahalogenated hydrocarbon, particularly fluoro-hydrocarbon. It is alsoknown in the art to perform this reaction in the presence of catalystsas, for example, organo-tin compounds having a carbontin bond or withtinoctoate, triethylenediamine, N- methylmorpholine or mixtures thereof.

In addition to the additives referred to and, particularly, if thefoaming is carried out in a single stage,polysiloxane-polyalkyleneglycol block copolymers are customarily addedto the system as foam stabilizers.

A satisfactory foam stabilizer for the indicated purpose should fulfilla number of requirements which, however, are only partially met by theprior art products as they are available on the market. It will thus beappreciated that it is, of course, of utmost importance that the blockcopolymer exhibits a high degree of stabilizing capacity which rendersit possible to operate with low amounts of foam stabilizers. Thepolysiloxane moiety in the block copolymer should,

moreover, be as small as possible, since the price of the stabilizer isvery much dependent on the amount of polysiloxane in the polymer. Thelower the amount of polysiloxane in the polymer, the lower the price.

Another desirable characteristicof an optimum foam stabilizer used forthe indicated purpose is that it should be relatively insensitive tochanges in the foaming composition. For example, it is desirable that,independent of the amount of tin or the like catalyst which may bepresent in the foaming system, the stabilizer should permit theformation of a foam homogeneous and uniform porosity. This, of course,is a most important criterion because it results in more uniformreaction products, the quality of which is relatively independent of theamount of catalysts in the system. Further, within certain fluctuationranges of the various ingredients, foams of substantially identical anduniform characteristics, particularly in respect to porosity are thusnevertheless obtained, which is a most desirable criterion.

Another task to be fulfilled by the foam stabilizer is that it shouldcause the propellent gas, which is formed during the reaction or whichhas been supplied to the foaming charge, to be effective in itspropellent action to a high degree so that foams of low density areformed. The formed foam should be as stable as possible so that uponshaping or forming no or only insignificant lasting deformation takesplace.

As is well recognized by those skilled in this specialized art, thecombination of the desirable features and effects enumerated above isnot achieved in present day foam stabilizers as available in commerce.

Accordingly, it is a primary object of this invention to provide a foamstabilizer for the indicated purpose which has all the desirablefeatures and effects referred to and which results, when used as a foamstabilizer in the foaming of polyurethane foams, in a foam of superiorquality and characteristics.

Another object of the invention is to provide a foam stabilizer of theindicated kind which is easy to manufacture at relatively low cost andfrom relatively readily available raw materials.

Briefly, and in accordance with this invention, it has surprisingly beenascertained that certain selected polysiloxane-polyalkyleneglycol blockcopolymers possess all the desired features and characteristics to makethem superior foam stabilizers for the indicated purpose.

The invention polysiloxane-polyalkyleneglycol block copolymerscorrespond to the general formula A B y, wherein A indicates thepolysiloxane moiety whose mole weight is between about 250 y to 1000 y,1.9 to 2.02 alkyl and alkoxy groups being present in the average persilicon atom, the alkyl and alkoxy groups containing one to four carbonatoms, at least 90 mole percent of the alkyl groups being methyl groupswhile the alkoxy groups are present in an amount of at the most 10 molepercent calculated on the alkyl groups;

B indicates the polyalkyleneglycolmonoalkyl or arylether moiety with amole weight of between about 2,400 to 5,000, wherein the alkyl has oneto six carbon atoms and the polyalkyleneglycol consists of alkyleneoxygroups of the formula Ala-011F0- and/or -(CH O- on the one hand and-(Cl-l O-- on the other, the weight ratio between the alkyleneoxy of theformulas B and C, and D, respectively being between 50:50 to :30 andwherein A and B are linked by divalent groups which preferably consistof oxygen, alkylene of one to four carbon atoms, the group (CH COO- or(Cl-l COO-.

Although y has been indicated to have a value of between 1.75 to 5, ithas been found that the preferred range is 2 3.5. In this connection, itshould be pointed out that the value for y may be relatively low if thepolyalkyleneglycolmonoalkylor arylether group has a high molecularweight within the indicated range.

As stated above, at least mole percent of the alkyl linked to siliconatoms are methyl groups. The remaining alkyl groups are preferablyethyl, propyl and isobutyl. Preferred alkoxy groups are those which arederived from a secondary alcohol. Examples for such alcohols areisopropyl alcohol and secondary butyl alcohol. The alkyl and/or alkoxygroups may be chlorinated without negatively affecting the result.

The polysiloxane moiety is essentially composed of structural units ofthe formula [R SiO] wherein R symbolizes the alkyl groups. In an averagepolymer molecule, there are preferably contained structural units of theformula [R sio lor 0 3 structural units of the formula [SiO Thepreparation of polysiloxane-polyalkyleneglycol block copolymers alwaysresults in the formation of mixtures of individual species of differentmolecular weight and distribution degree. In accordance with theinvention and for this reason, block copolymers are thus used whosepolysiloxane moiety is equilibrated or exhibits a relatively narrowmolecular weight distribution.

From the indication that the molecular weight of the polysiloxane moietyis between about 250 -y to 1000 y, it follows that the lower limit valuefor the molecular weight of the polysiloxane is about 437, the upperlimit value being about 5000. The preferred molecular weight for thepolysiloxane should be between about 600 to 3,250.

The alkyl group in the polyalkyleneglycol monoalkylether residue ispreferably n-butyl. In respect to the arylether, the respective group ispreferably phenyl which may be substituted. The polyalkyleneglycolresidue or moiety is composed on the one hand from a1- kyleneoxy groupsof the formula and/or (CH ),O and on the other hand from alkyleneoxygroups of the formula --(CH ),O. Within the first-mentioned group, thegroup of the formula ori-oniois preferred. If a portion of this group isreplaced by alkyleneoxy of the formula -(CH ).,O-, it must then beobserved that for the purpose of obtaining the same degree ofhydrophobic property, the ethyleneoxy content must be increased withinthe indicated limit values. Characterizing for the ratio of thealkyleneoxy of the formula and/or (CH ).,O to the alkyleneoxy of theformula --(CH O is a weight ratio of from 50:50 to 70:30. A weight ratiowithin this range of from 55:45 to 65:35 is particularly advantageous.The different alkyleneoxy groups within the polyalkyleneglycol moietyshould be present in statistical arrangement or in the form of smallblocks of at the most 5 units each. The preferred molecular weight rangeof the polyalkyleneglycol monoalkylor aryl-ether residue is 2,600 to3,000.

The polysiloxane moiety A and the polyalkyleneglycol moiety B are linkedto each other in the block copolymer by divalent groups. The linkage maybe effected by oxygen or an alkylene group. Particularly suitablealkylene groups are those containing one to four carbon atoms such as-CH -(CH,),-(CH CH,CH-CH,. Further, the groups (CH and (CH ),C0O- areparticularly suitable for causing the linkage between the moieties A andB.

It is possible to prepare the inventive poly-siloxanepolyalkylene glycolblock copolymers in a manner known per se. Block copolymers, wherein theblocks A and B are linked by oxygen may, for example, be

prepared corresponding to the teaching of German Pat.

Nos. 1,012,602 and 1,040,251 or U.S. Pat. No. 5 3,115,512. By contrast,block copolymers wherein the blocks A and B are connected by means of analkylene group can be prepared, for example, according to German Pat.No. 1,115,927. The preparation of block copolymers, wherein the blocks Aand B are connected by the group RCOO can be learned from U.S. Pat. No.2,991,300.

The invention will now be described by several Examples, it beingunderstood, however, that these Examples are given by way ofillustration and not by way of limitation and that many changes may beeffected without affecting in any way the scope and spirit of theinvention as recited in the appended claims.

EXAMPLEI A mixture consisting of 299 g of methyltrichlorosilane and3302.4 g of dimethyldichlorosilane was charged into a three neck flaskfitted with a drop funnel, stirrer and reflux condenser. 479 g of waterwere added to the flask in dropwise manner during 1 hour. The partialhydrolysis that took place was completed after 1 hour of stirring atroom temperature and after 1 hour of heating to 100 C and stirring atthis temperature for two and a quarter hours. After cooling to 50 C, 46g of 98 percent sulfuric acid were added to the reaction mixture andequilibration was effected for 18 hours at this temperature andsubsequently for two hours at 100 C. The siloxane obtained in thismanner had an acid value of about 1.8 X 10' val acid per g. To convertthe siloxane obtained in this manner to a stabilizer, 200 g of apolyethermonool of a molecular weight of 2700 with apropylene-ethyleneoxide ratio of 58:42 and 1.37 g of isopropanol in 520ml of toluene were added at 50 C to 50.1 g of the siloxane and themixture was stirred for 30 minutes. NH was subsequently introduced for30 minutes and after a reaction time of 1 hour, the toluene was removedby distillation at 9 mm Hg. After the addition of 30 ml of ethanol and 1ml of ethanolamine, stirring was effected at 70 C for 1 hour, theethanol was distilled off at 9 mm Hg, 1 ml of ethanolamine was added andthe reaction mixture was subjected to filtration.

The stabilizing capability of the stabilizer thus produced was tested bymeans of the following critical polyurethane foam formulation and wascompared with the stabilizing capability of a customary stabilizer as itis available on the market:

100 g of polyalkyleneglycol ether (OH number 55), 0.5 g of Sn-octoate,0.2 g of N-ethylmorpholine, 35 g of CFC1 6 g of water and between about0.4 and 2.2 g of stabilizer were foamed with toluylenediisocyanate(80/20) index 109.

The rising height or level of the foam was chosen as the measure for thestabilizing capability. The critical stabilizing concentration indicatesthe additional amount of stabilizer which is necessary in order toobtain a satisfactory foam. It corresponds to the height at whichsignificant retraction of the height of the sample is observed.

Height obtained with the inventive Height obtained with prior artstabilizer of the highest level 100 g of polyether stabilizer known as L520 of Union The critical stabilizer concentration with the inventivestabilizer is 0.4 parts. By contrast, with the prior art stabilizer thecorresponding concentration is between 1.8 and 2.0 parts, calculated on100 parts of polyalkyleneglycol.

EXAMPLE 2 In a manner analogous to that described in Example l, foamingtests were carried out with the following inventive stabilizer:

EXAMPLE 3 A foam stabilizer of the formula:

was prepared in known manner from equilibrated siloxane of the averageformula wherein l0 and 3 are average values, the siloxane having beenreacted with polyalkyleneglycolmonobutyl-' monoallylether POA againindicates a polyalkylene group having a molecular weight of 2700, theweight ratio of propylene oxide to ethylene oxide units being 60 to 40.The tests performed with this foam stabilizer showed resultscorresponding to those of Example 1.

EXAMPLE 4 The foaming tests were carried out in the presence of thefollowing stabilizer:

H: s Ha In this formula, T means either C H or a (POA) C l-I group inwhich 10 mole percent of the groups T are C H groups and mole percentare (POA) C H groups. POA again indicates a polyalkylene oxide blockwith the weight ratio of propyleneoxide to ethyleneoxide of 56 44, theblock having a mole weight of 3300. In the polyoxyalkylene block thedistribution of propyleneoxide and ethyleneoxide was such that, on theaverage, 3 propyleneoxide units were followed by 3 ethyleneoxide units,the last group being a propyleneoxide group which is then linked withthe Si atom.

The compounds were prepared in a manner known per se. First,triethoxypolysiloxane was produced by alkaline polymerization and wasthen re-esterified with polyalkyleneglycolmonobutylether.Trifluoroacetic acid was used as a catalyst.

Also this foam stabilizer yielded results equivalent to those obtainedwith the stabilizers of Examples 1 and 3.

While specific embodiments of the invention have been shown anddescribed in detail to illustrate the application of the inventiveprinciples, it will be understood that the invention may be embodiedotherwise without departing from such principles.

What is claimed is:

l. A polysiloxane-polyalkyleneglycol copolymer of the general formula AB y.

wherein 1.75 to 5;

A indicates the polysiloxane moiety of the block copolymer and beingcharacterized by a mole weight of between about 250 y to 1000 y, 1.9 to2.02 alkyl groups on the average being associated with each siliconatom, the alkyl groups containing one to four carbon atoms, at least 90mole percent of the alkyl groups being methyl and the remaining valencesof the silicon atoms being satisfied by alkoxy or siloxy units of theblock formula [R SiO], [R SiO and [SiO wherein R is alkyl, B indicatesthe polyalkyleneglycol monoalkylether moiety or polyalkyleneglycolmonoarylether moiety which is characterized by a mole weight of betweenabout 2,400 to 5,000, wherein the alkyl group has one to six carbonatoms and the polyalkyleneglycol residue is composed on the one hand ofalkyleneoxy groups of the formula and/or (CH ).,O and on the other handof the group (CH O in a weight ratio of about 50:50 to 70:30; and

wherein A and B are linked to each other by divalent groups beingoxygen, alkylene of one to four carbon atoms, (CH ),COO or (CH COO.

2. A block copolymer as claimed in claim 1, wherein y 2 to 3.5.

3. A block copolymer as claimed in claim 1, wherein the remaining molepercent of said alkyl groups of A are ethyl, propyl or isobutyl.

4. A block copolymer as claimed in claim 1, wherein the polysiloxanemoiety A is essentially composed of structural units of the formula [RSiOl wherein R symbolizes alkyl.

5. A block copolymer as claimed in claim 1, wherein the molecular weightof the polysiloxane moiety A is between about 600 to 3,250.

6. A block copolymer as claimed in claim 1, wherein the alkyl group ofthe polyalkyleneglycol monoalkylether moiety is n-butyl.

7. A block copolymer as claimed in claim 1, wherein the aryl group ofthe polyalkyleneglycol monoarylether moiety is phenyl or substitutedphenyl.

8. A block copolymer as claimed in claim 1, wherein the alkyleneoxygroups ofB are -CHCHZO C Hz and (CH O-. 9. A block copolymer as claimedin claim 1, which corresponds to the formula wherein n is on the average13 and POA symolizes a polyalkyleneoxide group composed of propyleneoxide and ethylene oxide in a weight ratio of about between 59:41, themole weight of POA being about 3,100.

10. A block copolymer as claimed in claim 1, which corresponds to theformula wherein POA symbolizes polyalkylene oxide of a mole weight ofabout 2,700 and consisting of propylene oxide and ethylene oxide in aweight ratio of about between 60:40.

11. A block copolymer as claimed in claim 1, which corresponds to theformula wherein T symbolizes C l-l or (POA) C 11 in which 10 molepercent of T is C 11 and mole percent (POA) C 11,, POA symbolizingpolyalkylene oxide composed of propylene oxide and ethylene oxide in aweight ratio of about between 56:44, the mole weight of POA being about3,300.

12. A block copolymer as claimed in claim 1, wherein alkoxy groups arecontained in said polysiloxane moiety, the amount of said alkoxy groupsbeing at the most 10 mole percent calculated on the alkyl groups.

13. A block copolymer as claimed in claim 12, wherein said alkoxy groupsof A are derived from a secondary alcohol.

14. A block copolymer as claimed in claim 13, wherein said secondaryalcohol is isopropyl alcohol or secondary butyl alcohol.

15. A block copolymer as claimed in claim 13, wherein said alkoxy groupsare chlorinated.

2. A block copolymer as claimed in claim 1, wherein y 2 to 3.5.
 3. Ablock copolymer as claimed in claim 1, wherein the remaining 10 molepercent of said alkyl groups of A are ethyl, propyl or isobutyl.
 4. Ablock copolymer as claimed in claim 1, wherein the polysiloxane moiety Ais essentially composed of structural units of the formula (R2SiO)wherein R symbolizes alkyl.
 5. A block copolymer as claimed in claim 1,wherein the molecular weight of the polysiloxane moiety A is betweenabout 600 to 3,250.
 6. A block copolymer as claimed in claim 1, whereinthe alkyl group of the polyalkyleneglycol monoalkylether moiety isn-butyl.
 7. A block copolymer as claimed in claim 1, wherein the arylgroup of the polyalkyleneglycol monoarylether moiety is phenyl orsubstituted phenyl.
 8. A block copolymer as claimed in claim 1, whereinthe alkyleneoxy groups of B are
 9. A block copolymer as claimed in claim1, which corresponds to the formula
 10. A block copolymer as claimed inclaim 1, which corresponds to the formula
 11. A block copolymer asclaimed in claim 1, which corresponds to the formula
 12. A blockcopolymer as claimed in claim 1, wherein alkoxy groups are contained insaid polysiloxane moiety, the amount of said alkoxy groups being at themost 10 mole percent calculated on the alkyl groups.
 13. A blockcopolymer as claimed in claim 12, wherein said alkoxy groups of A arederived from a secondary alcohol.
 14. A block copolymer as claimed inclaim 13, wherein said secondary alcohol is isopropyl alcohol orsecondary butyl alcohol.
 15. A block copolymer as claimed in claim 13,wherein said alkoxy groups are chlorinated.